Recently, an increase in power consumption by smart phones, tablet PCs and the like has derived development of various types of wireless charging devices (or chargers) for portable devices which should be frequently recharged. However, the wireless charging device has a narrow charging area due to a size of its transmitting coil. For an inductive wireless charging device, there has been a disadvantage in that a receiving coil of a portable device (or a mobile device) and a transmitting coil of the charging device should be aligned with each other at a (re)charging operation. Due to the narrow charging area, demands of product developers and consumers are increasing for a continuous increase in the charging area.
As a method for extending the charging area, there may be two methods, namely, changing a shape of a transmitting coil and moving the transmitting coil. As the method of changing the shape of the transmitting coil to increase the charging area, a charging device having transmitting and receiving coils in a triangular shape or an oval shape may be provided. As the method of moving the transmitting coil to increase the charging area, a charging device further having a transfer unit for allowing the transmitting coil to be movable on X and Y axes. When the shape of the coil is changed to increase the charging area, charging efficiency may be lowered. Also, for the charging device allowing the X and Y-axial movement of the transmitting coil, the charging area may be ensured without a reduction of charging efficiency but an increase in fabricating costs and difficulty in development and production may be caused due to mechanical complexity of the transfer unit.
Therefore, a method of ensuring a charging area without a reduction of charging efficiency and an increase in fabricating costs of a charger (or a charging device), with simplifying a mechanical structure, may be taken into account.